Disentangled Representation Learning in Heterogeneous Information Network for Large-scale Android Malware Detection in the COVID-19 Era and Beyond

In the fight against the COVID-19 pandemic, many social activities have moved online; society's overwhelming reliance on the complex cyberspace makes its security more important than ever. In this paper, we propose and develop an intelligent system named Dr.HIN to protect users against the evolving Android malware attacks in the COVID-19 era and beyond. In Dr.HIN, besides app content, we propose to consider higher-level semantics and social relations among apps, developers and mobile devices to comprehensively depict Android apps; and then we introduce a structured heterogeneous information network (HIN) to model the complex relations and exploit meta-path guided strategy to learn node (i.e., app) representations from HIN. As the representations of malware could be highly entangled with benign apps in the complex ecosystem of development, it poses a new challenge of learning the latent explanatory factors hidden in the HIN embeddings to detect the evolving malware. To address this challenge, we propose to integrate domain priors generated from different views (i.e., app content, app authorship, app installation) to devise an adversarial disentangler to separate the distinct, informative factors of variations hidden in the HIN embeddings for large-scale Android malware detection. This is the first attempt of disentangled representation learning in HIN data. Promising experimental results based on the large-scale and real sample collections from security industry demonstrate the performance of Dr.HIN in evolving Android malware detection, by comparison with baselines and popular mobile security products

Development of Wide-Angle Depolarizing Reflector at 1064 nm

Optical coherence tomography is a new promising chromatographic imaging technique with the advantages of noncontact and high resolution without damage, which is widely used in the field of biological tissue detection and imaging. As an important optical element in the system, the wide-angle depolarizing reflector plays a key role in the accurate acquisition of optical signals. Ta2O5 and SiO2 are selected as the coating materials for the technical parameter requirements of the reflector in the system. Based on the basic theory of optical thin film and combined with MATLAB and OptiLayer software, the design of 0~60° incident 1064 ± 40 nm depolarizing reflective film is realized by establishing the evaluation function of the film system. To optimize the oxygen-charging distribution scheme during film deposition, the weak absorption properties of the film materials are characterized by optical thermal co-circuit interferometry. According to the sensitivity distribution of the film layer, the optical control monitoring scheme with a thickness error of less than 1% is designed rationally. “Crystal control + optical control” is used to precisely control the thickness of each film layer and complete the preparation of resonant cavity film. The measurement results show that the average reflectance is more than 99.5%, and the deviation of P-light and S-light is less than 1% in the 1064 ± 40 nm wavelength band range from 0° to 60°, which meets the requirements of optical coherence tomography system

Self-Raman 1176 nm Laser Generation from Nd:YVO₄ Crystal by Resonator Cavity Coating

Crystal coating is an important process in laser crystal applications. According to the crystal characteristics of neodymium-doped yttrium vanadate (Nd:YVO4), its intrinsic parameters, and optical film design theory, Ta2O5 and SiO2 were selected separately as high and low refractive index materials. The optical properties and surface roughness of the films were characterized by OptiLayer and Zygo interferometers, and the effects of ion source bias on refractive index and surface roughness were investigated so that the optimal ion source parameters were determined. Optical monitoring and quartz crystal control were combined to accurately control the thickness of each film layer and to reduce the monitoring error of film thickness. The prepared crystal device was successfully applied to the 1176 nm laser output system

Pb₃[O₁₀Pb₂₀](SiO₄)₄X₁₀ (X = Cl, Br): The First Pb-Containing Halogen Silicates with Mirror-Symmetric Pseudo-Aurivillius Bilayers

Two new congruently melting Pb-containing halogen silicates, Pb3[O10Pb20](SiO4)4X10 (X = Cl, Br), have been synthesized using a high-temperature solution method. Their crystal structures were determined by single-crystal X-ray diffraction, and both compounds crystallize in the orthorhombic space group Cmca. In both structures, the mirror-symmetric bilayer composed of Pb–O polyhedra is observed for the first time in Pb-containing silicates and belongs to α-PbO derivatives and is related to the Aurivillius phase. Thermal behavior analysis, UV–vis diffuse-reflectance spectroscopy, and IR spectroscopy were also performed. The Pb3[O10Pb20](SiO4)4Cl10 matrix was doped with Eu3+ ions as a dopant, and its potential application in fluorescence was confirmed from the resulting orange-red emission